Patients will be identified and consecutively approached from each institution's Hepatology / Transplant Surgery and Interventional Radiology practices (by each site's Hepatology or Interventional Radiology co-investigators). An investigator or research coordinator will explain the study to the patient. The patient will be given time to consider the risks and benefits of the study and to ask questions about participation. A consent form will be reviewed with the patient. A full history and physical examination will be obtained from the patient's referring physician. If the subject is a woman of childbearing potential, she will have a urine pregnancy test prior to each CEUS study (the results of which will be made available to the subject prior to study initiation). In the event a patient presents with a lesion that is expected to be difficult to view on ultrasound (for example, smaller lesions located high on the liver dome), grayscale ultrasound imaging will quickly be performed to ensure the lesion is visible on ultrasound and that the patient is suitable for study inclusion.